Referring to FIGS. 1 and 2 a prior art single piece female electrical terminal 10 is depicted which is described in U.S. Pat. No. 5,720,634, issued Feb. 24, 1998 to Sten. This female electrical terminal is used for "plug through" type sealed electrical connectors, wherein an elastomeric seal is located at the cable end of the connector body. In this environment of operation, the electrical female terminals are inserted through holes in the seal as they are seated into the connector body, thereby sealing the cable with respect to the connector.
An attachment portion 12 at one end of the female electrical terminal 10 includes wire crimp wings 14 and cable crimp wings 16. At the opposite end, the female electrical terminal 10 has a contact portion 18. The contact portion 18 includes a split outer barrel 20 and a reduced diameter intermediate neck 22 which attaches the contact portion 18 to the attachment portion 12. The outer barrel 20 has two longitudinal edges 24 which define a split 26 when joined together.
A front end of the outer barrel 20 has a curled annular lip 28. Joined to the front end of the barrel 20 is a connection strap 30. The connection strap, when the outer barrel 20 is formed, is joined to the outer barrel generally opposite the longitudinal edges 24 (generally along the longitudinal centerline of the barrel). The connection strap 30 is folded rearwardly into the outer barrel 20. The connection strap juxtaposes two spring contact or support beams 32. The support beams 32 have an overall length represented by dimension 34. The support beams 32 have an overall length to length of joinder to the midstrap ratio of between 2.5:1 to 1.5:1. In the embodiment of FIG. 2, dimension 34 is 5.50 millimeters. The distance from the end of the contact beam to the outer barrel dimension 40 is approximately 0.75 millimeters.
A front portion of the support beams 32 form contact fingers 36. Preferably, section 38 of the contact fingers 36 will be plated with gold or like material to enhance contact interface characteristics. The remainder of the terminal may be copper or other suitable conductor.
The front edges of the contact fingers 36 extend toward the front end of the barrel 20 and are radially spring-biased inwardly when contacting a mating end (male pin) terminal (not shown). When fully formed, the support beams 32 and connection strap 30 form an inner barrel 42 which is almost essentially independent of the outer barrel 20. The contact fingers 36 typically will be inclined at 4 to 8 degrees and preferably 6 degrees from the axial centerline of the female electrical terminal. From the neck area 46, the intermediate neck 22 is formed, wherein a shoulder 45 is formed adjacent the intermediate neck 22 which serves as a positive lock location with respect to a lock abutment member of a connector.
The female electrical terminal 10 is formed from strip stock having an interface plating region which generally corresponds to section 38 of the contact fingers after forming. The first portion of the female electrical terminal 10 which is stamped is the connection strap 30 along with the support beams 32. As the female electrical terminal progresses down the assembly line, portions of the attachment portion are singulated from the rest of the stock material.
One of the advantages of the single piece configuration of the female electrical terminal 10 is the ability, as shown at FIG. 3, to optically inspect the female electrical terminal for manufacturing discrepancy. In the example depicted, a light source 48 shines a light beam 50 through a female electrical terminal 10', including a narrow intermediate neck 22', to an optical receiver 52. Optical inspection is mandated by the increasing dependence of reliable electrical interfacing in critical electrical circuits, such as for example those associated with supplemental restraint systems and anti-lock brake systems.
While the prior art female electrical terminal 10 performs well when configured at a size whereat the outer barrel 20 has a diameter of 2.00 millimeters (the intermediate neck having a diameter of 1.20 millimeters), there is a need to provide a single piece construction female electrical terminal which has a smaller diameter, yet retains the features of optical inspection and sealable interface with a connector. The smallest practical diameter of the outer barrel of the prior art female electrical terminal 10 is about 1.80 millimeters, and the smallest generally acceptable intermediate neck diameter thereof is about 0.90 millimeters. Problematically, if the female electrical terminal 10 is reduced in size below a diameter of 1.80 millimeters, the locking shoulder will become unacceptably ill-defined for positive locking in a connector and the neck area will become so reduced that strength and optical inspection are compromised.
Accordingly, what remains needed in the art is a miniaturized female electrical terminal of single piece construction which affords both positive locking in a sealed system type connector and ability to visually inspect for manufacturing irregularities wherein the outer barrel diameter is less than 1.80 millimeters.